Mediastinal tumors represent a heterogeneous group of diseases. The location of the mass is related to the clinical features and complications. Malignant masses of the anterior mediastinum are most frequent in children of precursor lymphoid neoplasms type leukemia/lymphoma, T lymphoma, Hodgkin’s lymphoma and germ-cell tumors. The emergency management of cancer caused by the compressive effect of the mass requires a comprehensive assessment and rapid intervention in order to preserve the patient’s life without sacrificing the optimal treatment later on. The superior vena cava syndrome, cardiac tamponade, and others are part of the most common mechanical emergencies.We present the a case of an 8 years old boy with respiratory symptoms, and the presence of an anterior mediastinal mass confirmed by flow cytometry as lymphoblastic lymphoma, who required treatment with steroids and chemotherapy for cytoreduction and improvement of complications.